1. Field
Embodiments of the present invention relate to a solenoid valve for a brake system, and more particularly, to a solenoid valve for a brake system capable of easily discharging air inside the solenoid valve and thus improving a control performance of the solenoid valve.
2. Description of the Related Art
A hydraulic brake system is installed in a vehicle as an essential element to perform a braking operation. In this regard, various brake systems have been recently suggested to provide more strong and stable braking force. Examples of the hydraulic brake system include an Anti-Lock Brake System (ABS) for preventing skid of wheels at the time of the braking, a brake traction control system (BTCS) for preventing slip of driving wheels at the time of a sudden acceleration incident or an unintended acceleration, and an electronic stability system (ESC) implemented as a combination of an ABS and a traction control to maintain a stable driving state of a vehicle by controlling a liquid pressure of a brake.
In order to implement a brake system, a modulator block has a plurality of solenoid valves that are electronically controlled, and a passage (a hydraulic circuit) is selectively open and closed by the solenoid valve. The solenoid valve is divided into a normal open type solenoid valve that remains normally opened, and a normal closed type solenoid valve that remains normally closed.
In general, the normal open type solenoid valve includes a magnet core provided at a center thereof with a through-hole formed lengthwise thereof and provided at a periphery thereof with an outlet, a domed sleeve installed at an upper portion of the magnet core, an armature installed inside the sleeve so as to be reciprocated, and an excitation coil installed at an outer side of the sleeve to reciprocate the armature.
Inside the through-hole of the magnet core, a plunger, a valve seat and a return spring are installed. The plunger is reciprocated according to an operation of the armature. The valve seat is provided with an orifice that is open and closed by the plunger. The return spring allows the plunger to be pushed toward the armature such that the orifice is open when power is not applied to the excitation coil.
The solenoid valve is installed on the modulator block to selectively open or close the orifice through the operations of the armature and the plunger, thereby controlling a flow of oil in the passage formed on the modulator block.